The present disclosure relates to an engine for a vehicle, such as a two-wheeled vehicle, and, more particularly, to an engine configured with variable valve timing for a motorcycle.
Conventional engines may be tuned and designed for various applications. For example, in one application, an engine may be tuned and designed for high-speed and high-horsepower performance, while in another application, an engine may be tuned and designed for fuel efficiency and lower emissions output. Such differences between these performance parameters of the engine may be at least partially controlled through the opening and closing timing of the intake and exhaust valves. The valve timing for opening and closing the intake and exhaust valves may be fixed, such that the intake and/or exhaust valves open at only one predetermined time and close at only one predetermined time, regardless of the performance parameters of the engine. However, depending on the vehicle, type of terrain, and other driving conditions, it may be desirable to vary the valve timing to allow opening and closing of the intake and exhaust valves at different crank angle position.
Various engines may use control devices which provide the ability to vary at least some parameters of the intake and/or exhaust valves. However, the location of such control devices may interfere with other engine or powertrain components and/or the user's ability to comfortably sit on and use the vehicle. For example, on a motorcycle, the user straddles the engine and any control device coupled to the engine for controlling the valve timing must be positioned at a location that does not interfere with operation of other engine components or the user's ability to use the foot controls and/or floorboard.
In this way, there is a need for a motorcycle engine configured with a variable valve timing system which is able to control the timing, duration, and amount of opening of the intake and/or exhaust valves.